High speed serial printing device for typewriters, teleprinters, calculating machines, accounting machines and the like

ABSTRACT

A high speed serial printing device comprises a continuously rotating drum circumferentially carrying a plurality of rows of characters which are to be struck by a hammer mounted on a carriage. A continuously rotating screw is synchronized with the drum and is engaged with a rack in order to move the carriage transversely. Each spiral of the screw includes a first portion which moves the carriage at a first speed while the hammer scans each row of characters, and a second portion which moves the carriage at a second speed which is higher than the first, while the hammer moves from a scanned row to an adjacent row of characters which are to be scanned.

United States Patent Bretti 1451 Dec. 19, 1972 54] HIGH SPEED SERIAL PRINTING DEVICE FOR TYPEWRITERS, TELEPRINTERS, CALCULATING MACHINES, ACCOUNTING MACHINES AND THE LIKE Franco Bretti, Are Di Caliiso, Italy [72] Inventor:

[73] Assignee: Ing. C. Olivetti & C.S.p.A.,' lvrea (Turin),Italy [22] Filed: June 2, 1970 [21] Appl. No.: 42,700

[30] Foreign Application Priority Data June 3, 1969 [52] U.S. Cl ..l97/55, 101/93 C, 197/20 [51] Int. Cl. ..B4lj l/22 [58] Field of Search .197/20, 55; 101/93 [56] References Cited UNITED STATES PATENTS 3,331,3l6 7/1967 Bretti ..197/1Rx ltaly ..s2093 A/69 Blodgett ..l97/20 Schiebeler l 97/] R Primary Examiner-Edgar S. Burr Attorney-Birch, Swindler, McKie & Beckett [57] ABSTRACT A high speed serial printing device comprises a continuously rotating drum circumferentially carrying a plurality of rows of characters which are to be struck by a hammer mounted on a carriage.

A continuously rotating screw is synchronized with the drum and is engaged with a rack in order to move I the carriage transversely. Each spiral of the screw includes a first portion which moves the carriage at a first speed while the hammer scans each row of characters, and a second portion which moves the carriage at a second speed which is higher than the first, while the hammer moves from a scanned row to an adjacent row of characters which are to be scanned.

5 Claims, 7 Drawing Figures PATENT Ennis 1 9 m2 3. 706; 367

sum 10F s INVENTOR. FRANCO BRETT! PATENTEDuEc 19 I972 SHEET 2 [IF 3 C211: 1 i I INVENTOR. FRANCO BRETTI PATENTED B 1912 3.706367 SHEET 3 BF 3 INVENTOR. FRANCO BRETT] HIGH SPEED SERIAL PRINTING DEVICE FOR TYPEWRITERS, TELEPRINTERS, CALCULATING MACHINES, ACCOUNTING MACHINES AND TH LIKE CROSS-REFERENCE TO RELATED APPLICATION Applicant claims priority from corresponding Italian patent application Ser. No. 52093-A/69 filed June 3, 1969.

BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a high speed serial printing device for typewriters, teleprinters, calculating and accounting machines and the like. The device includes a continuously rotating drum carrying a plurality of rows of characters, at least two rows of these characters being identical and being axially spaced according to the letter spacing. The device further includes a hammer operable for effecting the printing on the fly of the characters located on said drum, a screw continuously rotating in synchronism with said drum and means engageable said screw so as to transversely displace said hammer.

2. Description of the Prior Art High speed serial printing devices of the above mentioned type are known. In a known printing device, the hammer carriage is continuously moving in the transverse direction at a uniform speed and the hammer is operable for effecting the printing on the fly of the characters arranged on a continuously rotating drum. The hammer scans each row of characters, describing a helical trajectory with respect to the drum.

The width of each character should be substantially smaller than the letter spacing and therefore than the hammer face, so that the hammer can engage the entire face of each succeeding selected character.

This prior art printing technique produces characters adapted to be visually read and not machine read. Furthermore, the ratio between the letter spacing and the width of the character cannot be reduced, unless the blank portion of the drum is'increased; increasing the blank portion causes the speed of the machine to be reduced.

SUMMARY OF THE INVENTION In the printing device according to the invention, each spiral rib of the screw includes at least a first portion adapted to displace said hammer at a first speed while the hammer scans each row of characters and at least a second portion adapted to displace said hammer by a second speed higher than said first speed while said hammer moves from a scanned row to an adjacent row of characters to be scanned.

Further novel features and other objects of the invention will become apparent from the following description and appended claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partial sectional plan view of the serial printing device according to the invention;

FIG. 2 is a diagrammatical development of the type drum of FIG. 1;

FIG. 3 is a plan development of one spiral of the endless screw;

FIG. 4 is a partial cross sectional view according to line VII VII of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The instant printing device is an improvement of that described in U.S. Pat. No. 3,33 l ,316.

With reference to the FIG. 1', the printing device includes a type drum 11 secured to a transverse shaft 12 which continuously rotates on the machine frame. The drum 11 carries a plurality of series or rows 13 (FIG. 2) of decimal characters from to 9, of which only the extreme rows are shown in FIG. 2. The rows 13 are identical to and parallel to each other about the circumference of the drum 1 l. The rows are spaced according to the letter spacing and extend approximately l80around the circumferential surface of the drum. The remaining l80of the circumferential surface, blank portion 10, has no characters or symbols thereon. Each row 13 contains a character for a decimal point and a character for the minus sign. Furthermore the drum 11 carries a row 14 of symbols indicative of the various functions which the calculating machine can carry out. The decimal characters and the symbols are adapted for optical or magnetic readmg.

At the left end of the shaft 12 (FIG. I) a pulley I is secured which has teeth about its circumferential surface in order to prevent slippage. The pulley 15 is connected by means of a toothed belt 16 (FIG. 5) to a second toothed pulley 17 secured to a shaft 18 continuously rotating on the left side wall 19 (FIG. 1) of the machine frame. The diameter of pulley 17 is twice the diameter of pulley l5. Shaft 18, a square shaft 21 and a shaft 22 which are rotatable on right side wall 23 of the frame, are constructed from a single length of metal.

The printing device comprises a carriage generically indicated at 24 which includes two side members or walls 26 connected by a transverse member 27 and by a sleeve 28 (FIG. 4) slidable on a shaft 29 secured to the machine frame. Each wall 26 is provided with a slot 30 transversely slidable on a stationary shaft 31. A spring 32 (FIG. I) normally biases the carriage 24 against an elastic stop 33 fixed on the shaft 29. A hammer 34 (FIG. 4) rotatable about the sleeve 28 is guided by a slot 35 (FIG. I) of the transverse member 27 and a spring 36 (FIG. 4) normally biases the hammer 34 against the closed end position of the slot 35.

A universal bar 38 (FIG. I) secured to two lugs 39 of a bail 40 can cooperate with a shoulder 37 of the hammer 34. The bail 40 is fulcrumed on a shaft 41 secured to two side members 42 of a plate 43, which plate is integral with the machine frame. The bar 38 extends transversely to engage shoulder 37 of the hammer 34 as hammer 34 is displaced transversely with the carriage 24. Secured to a transverse member 44 (FIG. 4) of the bail 40 is a movable member 45 of an electromagnet 46. A spring 47 normally biases the transverse member 44 against two stop members 48.

The two walls 26 (FIG. 1) of the carriage 24 are providecl with two projections 49 which receive shaft 21 in a slot 50 (FIG. 4). A screw 51 (FIG. 1) is disposed between the two projections 49 and continuously rotates together with the square shaft 21. The screw 51 is axially slidable on the shaft 21. Each 360spiral 52 of the screw 51 has a pitch ranging between two values P1 and P2, as shown in FIG. 3, wherein one spiral 52 of R radius is shown in a plane. In particular, the spiral 52 is comprised of two portions E1 and E 3 having a pitch P1 and two portions E2 and E4 having a pitch P2. PM represents the average pitch of the spiral 52. PM is intermediate between the two pitches P1 and P2 and is twice the letter spacing. The screw 51 comprises tow and one-half spirals 52.

A cam 56 is secured to the shaft 18 (FIG. 1). Cam 56 engages a projection 57 of a bail 58 (FIG. The bail 58 is rotatably and transversely slidable mounted on shaft 59 which is in turn rotatable on the machine frame. The bail 58 is provided with another projection 61 axially offset with respect to the lug 57, which projection 61 normally lies on the left of the cam 56 (FIG. 1). A slot 62 of the bail 58 engages a lug 63 of a lever 64 fulcrumed on a stationary pin 66, which lever 64 is connected by means of a pin and slot to a moveable element 68 of an electromagnet 69. The bail 58 is furthermore provided with a pin 71 (FIG. 5) which is engaged by a slot 72 of a lever 73 secured to the shaft 59. A pin 76 of a lever 77 which is fulcrumed at 78, is adapted to cooperate, by means of a spring 79, with a positioner tooth 74 of the lever 73.

A spring 81 (FIG. 1), which is hooked to the lever 64, biases the ball 58 against a sleeve 82 which is slidable on the shaft 59. The sleeve 82 is secured to a side member 83 of a bail 84, and the spring 81 normally biases the member 83 against the wall 19. The bail 84 is rotatably and transversely slidably mounted on the shaft 59. The side member 83 is provided with two embossed elements 86, 87 which normally engage two corresponding holes 88, 89 of the side wall 19 of the device. A side member 91 of the bail 84 is provided with a lug 92 which is adapted to cooperate with an arm 93 of a bail 94. The lug 92 is normally above the arm 93 (FIG. 4). The bail 94 is fulcrumed on the shaft 59 and is provided with a second arm 96. A spring 98 biases an appendage 97 of the arm 96 against a pin 99 ofa lever 101. The lever 101 is fixed to the shaft 59, whereas the spring 98 is stretched between the lever 101 and a second appendage 102 of the arm 96.

A rack 104 is fixed to the bail 94, and has inclined teeth 106 (FIG. 1). The teeth 106 are adapted to engage the endless screw 51 and are spaced according to a pitch which is equivalent to two letter spaces. A notch 107 between two adjacent teeth 106 is substantially larger than the width of a spiral 52. After the rack 104 has engaged the screw 51 as below described, the spring 32 biases the spirals 52 against the left side of the teeth 106, which teeth are rounded lengthwise. The spirals 52 do not contact the right side of the teeth 106.

The operation of the printing device is the following.

The pulley 17 (FIG. 5) normally rotates counterclockwise together with the eccentric 56, the shaft 18, the square shaft 21 and the shaft 22 (FIG. 1). The belt 16 rotates the toothed pulley and the type drum 11 in the same direction at an angular velocity double that of the pulley 17. After the calculating machine has processed 'data to be printed, an output signal is produced, which signal energizes the electromagnet 69 at any particular time, regardless of the particular angular position of the drum 11. The electromagnet 69 attracts the element 68 which rocks the lever 64 counterclockwise. The lever 64 by means of the lug 63 displaces the bail 58 transversely so that the projection 57 moves to the right out .of the plane of the cam 56, and the projection 61 then moves into the operative plane of cam 56. Cam 56 now rotates the bail 58 counterclockwise, and bail 58 in turn rotates the lever 73 and the shaft 59 in the same direction by means of the pin 71.'The lever 73 is held in the new position by the pin 76, after pin 76 has stopped over thetooth 74.

The lever 101 (FIG. 4) rotates counterclockwise together with the shaft 59, and the pin 99 retracts so that the spring 81 causes the bail 94 to rock in the same direction. The rack 104 thus rises so that the teeth 106 engage the screw 51.'This engagement occurs when the spirals 52 is able to enter into the notches 107. The engagement becomes effective when the spirals 52 start sliding on the left sides of the teeth 106, in correspondence with a fixed angular position of the screw 51 and the drum 1]. In effect, the spirals 52 contact the teeth 106 in the center of the portions E2 or E4 having the pitch P2 (FIG. 3). At the moment when the spirals 52 engage the teeth 106, the center of the blank portion 10 (FIG. 2) of the type drum 11 faces the hammer 34.

Beginning at this moment, the screw 51 (FIG. 1) sets the carriage 24 in motion to the left at such an initial speed that the carriage moves through one eighth of the pitch P2 while the shaft 21 rotates through 45. During such first displacement of the carriage 24, the drum 11 rotates through and the hammer 34 describes, with respect to the drum 1 l, a first portion of a helical path indicated at A in FIG. 2. Then the portion having pitch P1 of the spirals 52 engages the teeth 106, whereby the carriage 24 is set in motion with a second speed which is lower than the initial speed. At this time the carriage 24 moves through one fourth of pitch P1 while the shaft 21 rotates through 90. At the same time the drum 11 rotates through and the hammer 34 describes, with respect to the drum 11, a second portion of the helical path indicated at B in FIG. 2, substantially less inclined than the first portion. While traversing said second portion, the hammer 34 scans the row 14 of the symbols.

Subsequently, the portion having pitch P2 of the spirals 52 engages the teeth 106 so that the carriage 24 moves according to the initial speed while the shaft 21 rotates through 90 and the drum 11 rotates through 180. In FIG. 2 a third portion of the helical path is indicated at C. This third portion is of the same inclination as the A portion described by the hammer 34. The FIG. 2 shows that the B portion of the path is less inclined than the A and C portions which correspond to the blank portion 10 of the drum 1 1.

As. soon as the carriage 24 has started moving, the machine produces a signal which represents a character. The electromagnet 46 (FIG. 4) is then energized and the bail 40 rocks clockwise, and the universal bar 38 causes the hammer 34 to strike the drum 11 thereby printing the selected character. This is more fully described in the aforesaid patent. During the I060 I l 0043 scanning operation of each row 13 of characters (FIG. 2) the hammer 34 follows the above described helicoidal path for the symbol row 14 and the electromagnet 44 (FIG. 3) is energized each time, in a manner known per se, for printing the selected characters. After the printing of the most significant order of an amount, which may be represented by a zero to the left of the decimal point, the machine produces a minus signal if the algebraic sign of the printed amount is negative. This sign is printed to the left of the amount. If the algebraic sign of the amount is positive, the machine produces no signal.

At this point, the electromagnet 69 (FIG. 1) is deenergized, and the spring 81 biases the lever 64 clockwise and the bail 58 returns to the axial home position, in which position, the bail 58 contacts the sleeve 82. The projection 61 moves out of the operative plane of the cam 62, whereas the projection 57 engages the cam 62. The latter rocks the bail 58 clockwise, resetting it to the angular position of FIG. 5. The pin 71 of the bail 58 rotates the lever 73 in the same direction, and the pin 76 engages the right side of the tooth 74. The shaft rotates clockwise, together with the lever 101 (FIG. 4) so that the pin 99 lifts the appendage 97. Consequently the bail 94 rocks clockwise and the rack 104 disengages from the screw 51. The carriage 24 (FIG. 1) is again displaced to the right to its home position by the spring 32 until it stops against the elastic stop 33.

The printing operation occurs on the conventional strip of paper 108 (FIG. 4) which is fed from a roll 109 and is guided around the drum 11 by a paper guide plate 111 to keep the strip 108 slightly displaced from the drum 11. Plate 111 is provided with a slot 112 which extends along the entire length of the plate 111 and is placed to the rear of the hammer 34 in each transverse position of hammer 34. The strip 108 is pressed against a drum 113 by the action of a lower roller 114 and an upper roller 116, which rollers are placed on the right side end of the drum 113. The drum 113 is secured to a shaft 117 rotatable in two seats of the machine frame. The roller 116 is carried by a lever 118 fulcrumed on a shaft 119, whereas the roller 114 is carried by a lever 121 secured to a shaft 122 which is rotatable on two seats of the machine frame.

A spring 123 stretched between the levers 118 and 121 biases the rollers 114 and 116 against the drum 113. A key 124 is fixed on a lever 126, which lever is fulcrumed at 117. A spring 128 biases the lever 126 against a stop 127. A shoulder 129 of the lever 126 is adapted to cooperate with a pin 131 of the lever 121. Two other rollers 132, 133 (FIG. 6) hold the paper 108 pressed against the left side of the drum 113. The roller 132 is carried by a lever 134 secured to the shaft 122. The lever 134 is provided with a pin 136 adapted to cooperate with a lever 137 fulcrumed on the shaft 119., which lever carries the roller 133 at one of its ends. A spring 139 stretched between the levers 134, 137 biases the rollers 132, 133 against the drum 113. The lever 134 is provided with a lug 141, and a spring 144 biases a shoulder 142 ofa lever 143 against the lug 141.

Another key 146 is connected to a lever 147 fulcrumed on the shaft 117 and a spring 149 biases the lever 147 against the stop 127. The lever 147 is provided with a lug 51 adapted to cooperate with the lever 143. The lever 147 is provided also with an appendage 152 adapted to engage a lug 153 of a lever 154 fulcrumed on the shaft 122. The lever 154 is provided with a fork 156, which engages a pin 216 ofa lever 217 fulcrumed on a stud 218. A lever 219 fulcrumed on the shaft 117 carries the stud 218. The lever 217 is provided with a tooth 221, which is engaged by a line spacing toothed wheel 222 secured to the shaft 117, whereas the lever 219 is provided with a bent lug 223 adapted to cooperate with the lever 217. A spring 228 biases a roller 224 into a notch of the toothed wheel 222. The roller 224 is carried by a lever 226 fulcrumed on 227.

When a paper strip 108 is to be inserted into the machine, the key 124 (FIG. 4) is depressed. The shoulder 129 of the lever 126 lowers the pin 131, the lever 121 rotates counterclockwise and therefore the roller 114 moves from the drum 113. Furthermore the pin 131 causes the lever 118 to rock clockwise and causes the other roller 1 16 to move from the drum 113. The shaft 122 rotates counterclockwise together with the lever 121. Shaft 122 imparts the same rotation to the lever 134 (FIG. 6), whereby the roller 132 moves from the drum 113. Furthermore, the lever 134 causes the lever 137 to rock clockwise by means of the pin 136 and causes the roller 133 to move from the drum 113. If the key 124 (FIG. 4) is depressed in such manner so as to cause the lug 141 (FIG. 6) to pass beside the shoulder 142, the lever 143 rotates counterclockwise and locks the lever 134 in the rotated position, whereby the left side rollers 132, 133 and the right side rollers 114, 116 remain separated from the drum 113.

After the paper strip 108 has been inserted between the rollers 114, 132 (FIGS. 4 and 6) and the drum 113, the paper 108 is driven in front of the plate 111 and finally it is inserted between the rollers 116, 133 and the drum 113. Then the key 146 (FIG. 6) is lowered and rocks the lever 143 clockwise by means of the lug 151 of the lever 147. Consequently, the shoulder 142 releases the lug 141, whereby the lever 134 is reset into the position shown in (FIG. 6) by the urge of the spring 139. The four rollers 114, 116, 132 and 133 are again pressed against the drum 113 so that the paper 108 is held firmly against the drum.

After electromagnet 69 (FIG. 5) has been energized, the printing operation starts, the lever 73 rocks counterclockwise and the lever 217 rocks in the same direction about the pin 218 on the lever 219. The tooth 221 disengages from the wheel 222. Subsequently the lever 217 contacts the lug 223 of the lever 219 in such manner that a further rocking of the lever 73 causes the lever 219 to rock clockwise on the shaft 117 to predispose the tooth 221 to engage the next following tooth of the wheel 222. As soon as the electromagnet 69 is released after the amount has been printed, the lever 73 is restored to its home position, the lever 217 rocks clockwise, and the tooth 221 reengages the wheel 222. The lever 73 rotates the wheel 222 counterclockwise and the paper strip 108 (FIG. 4) moves through a line spacing. The roller 224 now engages the subsequent notch of the wheel 222, and holds the wheel 222 in the new angular position.

In the case the paper strip 108 is to be advanced through one or more line spacings, independently from the printing operation, the key 146 (FIG. 6) must be depressed. The appendage 152 of the lever 147 rotates the lever 154 counterclockwise, which in turn rocks the bail 84 clockwise and the two embossed elements 86, 87 (FIGS. 1 and 6) disengage from the holes 88, 89 of the side wall 19. The bail 84 moves transversely, together with the bail 58, through a shifting that causes both projections 57, 61 to become engaged by the cam 56. The bail 58 is now able to rock between the home position represented in FIG. and an operative position which is advanced more in the counterclockwise direction than the home position.

Therefore, as long as the key 146 (FIG. 6) is kept in the depressed position, a line spacing is effected by means of the lever 73 in conjunction with each turn of the cam 56. When the continuous line spacing key 146 is depressed, the bail 84 rotates clockwise and lowers the lug 92 which engages the arm 93 (FIG. 4) of the bail 94, so that the rack 104 cannot engage the screw 51 when the cam 56 (FIG. 5) causes the bail 58, the shaft 59 and the lever 101 (FIG. 4) to rotate counterclockwise.

The imprint on the paper strip 108 is obtained by means of an ink ribbon 162 (FIG. 1), which is wound on two spools 163, 164. The spools 163, 164 are inserted on two shafts 166, 167 respectively which are rotatable on a spool support plate 168. A toothed wheel 169 is secured on the shafts 166,167. The wheel 169 cooperates with one of the teeth 171 of a lever 172 fulcrumed at 173 on slide 174. The teeth 171 contact a corresponding stop plate 177 under the urge ofa spring 176, said plate 177 being controlled by a ribbon reversing device known per se. The two slides 174 are provided with two slots 184, 186 which are adapted to slide on two pins 187, 188 that are secured to the plate 168 and connected to a transverse member 194. The member 194 is integral with an arm 196 which is at right angles to member 194.

The arm 196 engages an arm 198 of a bail 199 by means of a pin 197 (FIG. 7), said bail 199 being fulcrumed on a stationary shaft 201. The bail 199 is provided with another arm 202 which engages an arm 204 of a bail 206 fulcrumed on the shaft 59, by means of a pin 203. The bail 206 is provided with a lug 207 which contacts a shoulder 211 of the arm 102 of the bail 94 under the action of a spring 208. A roller 212 of the bail 206 is adapted to cooperate with a second cam 213 secured to the shaft 22.

After the electromagnet 69 (FIG. 1) has been energized, the printing operation is started. The shaft 59 (FIG. 7) allows the bail 94 to rock in the same direction under the urge of the spring 98. The shoulder 211 of the bail 94 releases the lug 207 of the bail 206. The spring 208 causes the bail 206 to rock counterclockwise whereby the roller 212 engages the cam 213. The bail 206 is now oscillated and the arm 204 causes the bail 199 to rock together with the bail 206. The arm 198 moves the arm 196 and the two slides 174 (FIG. 1) forward and backward. Consequently, the ribbon 162 moves step by step under the control of the ribbon reversing device. Therefore, as long as the printing is being carried out the ribbon feeding operation will also be effective. As soon as the electromagnet 69 is deenergized, namely after a line has been printed, the ribbon feeding operation ceases.

What 1 claim is:

1. In a high speed serial printing device, the combination comprising:

time

a continuously rotating type drum, a plurality of rows of characters carried by said drum, at least two of said rows of characters being identical and being axially spaced according to the letter spacing, said rows being circumferentially arranged on a first portion of the circumference of said drum, said drum having a second of its circumference portion devoid of characters,

a hammer operable to effect the printing of said characters on the fly,

a screw continuously rotating in synchronism with said drum, said screw being formed of at least one spiral rib wound through 360, said spiral rib having a first portion of a first predetermined inclination and a second portion of a second predetermined inclination greater than said first inclination,

connecting means engaging said spiral rib and connected to said hammer to transversely displace said hammer one letter space for each revolution of said drum so that said hammer can scan said drum, said spiral rib and said drum being so oriented with respect to one another that said first portion of said spiral rib is engaged by said connection means when said hammer is scanning said first portion of said drum and said second portion of said spiral rib is engaged by said connecting means when said hammer is scanning said second portion of said drum, whereby said hammer is transversely displaced at a first speed when scanning said first portion of said drum and at a second speed greater than said first speed when scanning said second portion of said drum.

2. A device according to claim 1 wherein the pitch of said screw is a multiple of said letter spacing, and said screw and said drum are interconnected by a motion reducing means having a ratio corresponding to said multiple, and wherein each said spiral rib comprises a plurality of said first and second portions of predetermined inclination equal in number to said multiple.

3. A device according to claim 1, further comprising:

a machine frame,

a carriage transversely movable on said frame, said hammer and said screw being mounted on said carriage,

a rack comprising a part of said connecting means mounted on said frame and engageable with said screw, and

a control member connected to said rack and controlling the engagement of said rack with said screw, said control member normally being located in a first position holding said rack disengaged from said screw and being shiftable to a second position placing said rack in engagement with said screw.

4. A device according to claim 3 wherein said rack is movable toward and away from said screw and is biased toward said screw, and wherein said control member is operated by a continuously rotating cam means in synchronism with said screw, said control member comprising a pair of opposed elements engageable with said cam, one of said elements when engaged by said cam operating said control member to move said rack against said bias out of engagement with said screw and the other of said elements when engaged by said cam operating said control member to allow said rack to move into engagement with said screw under the action position from said second position to rotate said f Said i paper guiding drum one step,

5. A device according to claim 4 further comprising: continuous spacing control means operatively intera F p guiding drum Spaced from and Parallel connectable with said control member to hold said said type drum. 5 control member in an intermediate position leflst f" P of Pa gulde P coopFrafing between said first and second positions to cause with sand paper guiding drum, said paper guide rolsaid pawl to rotate Said paper guiding drum lers in each said pair being substantially diametrically opposite one another with respect to said paper guiding drum, 10 a pawl engageable with said paper guiding drum and operatively interconnected with said control member, said pawl engaging said paper guiding drum as said control member returns to said first peatedly to effect a continuous space, and

a locking element operated by said continuous spacing control means holding said rack disengaged from said screw which said control means is operated.

In. l060ll 0046 

1. In a high speed serial printing device, the combination comprising: a continuously rotating type drum, a plurality of rows of characters carried by said drum, at least two of said rows of characters being identical and being axially spaced according to the letter spacing, said rows being circumferentially arranged on a first portion of the circumference of said drum, said drum having a second of its circumference portion devoid of characters, a hammer operable to effect the printing of said characters on the fly, a screw continuously rotating in synchronism with said drum, said screw being formed of at least one spiral rib wound through 360*, said spiral rib having a first portion of a first predetermined inclination and a second portion of a second predetermined inclination greater than said first inclination, connecting means engaging said spiral rib and connected to said hammer to transversely displace said hammer one letter space for each revolution of said drum so that said hammer can scan said drum, said spiral rib and said drum being so oriented with respect to one another that said first portion of said spiral rib is engaged by said connection means when said hammer is scanning said first portion of said drum and said second portion of said spiral rib is engaged by said connecting means when said hammer is scanning said second portion of said drum, whereby said hammer is transversely displaced at a first speed when scanning said first portion of said drum and at a second speed greater than said first speed when scanning said second portion of said drum.
 2. A device according to claim 1 wherein the pitch of said screw is a multiple of said letter spacing, and said screw and said drum are interconnected by a motion reducing means having a ratio corresponding to said multiple, and wherein each said spiral rib comprises a plurality of said first and second portions of predetermined inclination equal in number to said multiple.
 3. A device according to claim 1, further comprising: a machine frame, a carriage transversely movable on said frame, said hammer and said screw being mounted on said carriage, a rack comprising a part of said connecting means mounted on said frame and engageable with said screw, and a control member connected to said rack and controlling the engagement of said rack with said screw, said control member normally being located in a first position holding said rack disengaged from said screw and being shiftable to a second position placing said rack in engagement with said screw.
 4. A device according to claim 3 wherein said rack is movable toward and away from said screw and is biased toward said screw, and wherein said control member is operated by a continuously rotating cam means in synchronism with said screw, said control member comprising a pair of opposed elements engageable with said cam, one of said elements when engaged by said cam operating said control member to move said rack against said bias out of engagement with said screw and the other of said elements when engaged by said cam operating said control member to allow said rack to move into engagement with said screw under the action of said bias.
 5. A device according to claim 4 further comprising: a paper guiding drum spaced from and parallel to said type drum, at least one pair of paper guide rollers cooperating with said papeR guiding drum, said paper guide rollers in each said pair being substantially diametrically opposite one another with respect to said paper guiding drum, a pawl engageable with said paper guiding drum and operatively interconnected with said control member, said pawl engaging said paper guiding drum as said control member returns to said first position from said second position to rotate said paper guiding drum one step, continuous spacing control means operatively interconnectable with said control member to hold said control member in an intermediate position between said first and second positions to cause said pawl to rotate said paper guiding drum repeatedly to effect a continuous space, and a locking element operated by said continuous spacing control means holding said rack disengaged from said screw which said control means is operated. 